[Haskell-cafe] Error in Installing Data.deriveTH

mukesh tiwari mukeshtiwari.iiitm at gmail.com
Fri Sep 16 13:55:25 CEST 2011

Thank you for reply Daniel . I installed the ghc-7.2.1 but now running
cabal install keys  --dry-run -v gives error. One more thing i would like to
know. Before installing any package , i should check its dependency and if
it depends on any global namespace package [/usr/local/lib/ghc-7.2.1/package
.conf.d ] so i should not install the global namespace package using cabal
install <global-package> otherwise it will hide the global package. I should
only install those packages which are not in global namespace. Am i correct
?  Any idea how to remove this error .

ntro at ntro-HP-dx2480-MT-NA121PA:~/Mukesh/Haskell$ ghcghc-7.2.1
ghci-7.2.1     ghc-pkg-7.2.1
ntro at ntro-HP-dx2480-MT-NA121PA:~/Mukesh/Haskell$ cabal install keys
--dry-run -vcabal: The program ghc version >=6.4 is required but it
could not be foundntro at ntro-HP-dx2480-MT-NA121PA:~/Mukesh/Haskell$
cabal --vcabal-install version 0.10.2using version of the
Cabal libraryntro at ntro-HP-dx2480-MT-NA121PA:~/Mukesh/Haskell$
ghc-pkg-7.2.1 list/usr/local/lib/ghc-7.2.1/package.conf.d
   transformers- at ntro-HP-dx2480-MT-NA121PA:~/Mukesh/Haskell$
which  ghc-7.2.1/usr/local/bin/ghc-7.2.1ntro at ntro-HP-dx2480-MT-NA121PA:~/Mukesh/Haskell$
echo $PATH/home/ntro/.cabal/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/gamesntro at ntro-HP-dx2480-MT-NA121PA:~/Mukesh/Haskell$
which cabal/home/ntro/.cabal/bin/cabal

On Fri, Sep 16, 2011 at 4:18 AM, Daniel Fischer <
daniel.is.fischer at googlemail.com> wrote:

> On Thursday 15 September 2011, 21:37:29, mukesh tiwari wrote:
> > I tried to resolve this issue on #haskell and i got suggestion that it
> > was due to conflict in
> >
> > global and local namespace [ see here for more detail
> > http://hpaste.org/51376 ].
> Yes.The containers in the global db is shadowed by the user containers.
> > One idea is i should wipe ~/.ghc and install all the libraries
> > individually.
> That'll work. If there are only few packages broken, unregistering only
> those could be less work.
> $ ghc-pkg check
> should indicate whether there's a chance that surgical removal of
> individual packages might be worthwhile. If the breakage is recent and only
> few packages are affected, it is, otherwise wiping out the entire user db
> would likely be simpler.
> > Could some one please suggest if there is another idea to
> > resolve this issue.
> There is no fundamentally different way, the only method to fix broken
> packages is to remove them. The only question is whether it's better to get
> completely rid of the entire user db [and if you have the bad luck of
> having breakage within the global db by doing global installs, you'd
> probably need an entire new ghc installation] or only of individual
> packages.
> > Currently i have ghc-6.12.3  and  installing
> > ghc-7.0 will resolve the issue ?
> In a certain sense, yes. With a new version of ghc, you start with a clean
> slate without broken packages. However, you could pretty much introduce the
> same kind of breakage with that.
> Generally, it's a bad idea to reinstall any library that came with the ghc
> installation (there are some exceptions, e.g. installing a newer version of
> Cabal has a fair chance of not causing havoc).
> As rules of thumb,
> - don't mess with the global db, user installs only
> - don't install any library which already has a version in the global db[*]
> - be careful when upgrading any library, it could break everything
> depending on that.
> Of course, if you know what you're doing, there can be good reasons to
> break any of these rules, but if you don't know why it's right, it's
> probably wrong.
> Although it's tedious, checking all cabal install with a --dry-run first
> helps avoiding breakage.
> [*] and if you do, the more packages you have installed, the more likely it
> will break some of those.
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